The processing of various materials through use of a laser beam is well known, and includes welding, cladding and the like. These various processes all involve the targeting of the beam on the workpiece and, generally, some relative movement is effected between the beam and the workpiece. It is important that the targeted spot and/or the beam be monitored to make sure that the operation is performed as uniformly as possible. Failure to correct for irregularities in any one of a number of beam or workpiece parameters can result in the finished workpiece being unusable.
Various devices are known which cooperate with the laser for targeting the beam on the particular spot on the workpiece. These include a cooperative beam which illuminates the targeted spot in conjunction with the laser beam and which is monitored to assure proper targeting. Furthermore, it is known to monitor the power of the beam, such as by an acoustic mirror.
None of these prior systems, however, makes use of the laser beam itself for monitoring the various parameters of the beam and the workpiece. A substantial amount of information is inherently transported by the beam, as well as by the back reflected beam from the targeted spot, and this information may be interpreted to generate data concerning speed of movement, coupling efficiency and height detection, among other parameters.
In view of the above, it can be seen that there is a need for a beam monitor which makes use of the information inherently transported with the incident beam and with the back reflected beam. The disclosed invention is just such a monitor which continuously compares a selected characteristic of the incident beam with the same characteristic of the back reflected beam, and thereby monitors some particular parameter or parameters of interest. The disclosed invention is an apparatus and a method of using the apparatus which permits precise control to be obtained over the processing operation.